The present invention relates to a novel composition and method for hydrophobizing leathers and leather substitutes by treatment with an aqueous dispersion of an unreacted mixture of relatively inert dimethyl silicon and ammonium oleate, or a like ammonium salt of a fatty acid having between 12 and 22 carbon atoms.
Various methods and compositions are known in the art for enhancing the water resistance of leather and leather-like materials, such as pelts, skins, and leather substitute materials. For example, U.S. Pat. No. 4,931,062, Bay et al, discloses a process for waterproofing leather by using a polysiloxane which has been neutralized to form the salt of a carboxyl-containing polysiloxane. Hydrophobization is effected, according to Bay et al, by drumming in the conventional manner, during or after retaining. U.S. Pat. No. 4,701,269, also to Bay et al, discloses a similar process for treating leathers which is carried out in the aqueous phase using silicon oil and the salt of an N(C.sub.9 -C.sub.20 -acyl)-amino acid as an emulsifier for the silicon oil.
Other methods, known in the art, for hydrophobizing articles include the use of dialkyldialkoxysilane and alkyl trialkoxysilane with a colloidal silica, as disclosed in U.S. Pat. No. 4,170,690, to Armbruster et al; the use of organopolysiloxanes having a viscosity of 1,000 to 1,000,000 centipoise in a mixed liquid suspension for colloidal, as disclosed in U.S. Pat. No. 4,258,102, to Traver et al; and dipping an article in a bath of silicone or hydrofluorocarbon, as disclosed in U.S. Pat. No. 4,369,231, to West et al. Further, other methods which have achieved a high degree of hydrophobicity of the article to be treated have been specific to those base stocks with an open web, such as fabrics. U.S. Pat. No. 5,209,695, and U.S. Pat. No. 5,004,643, both to Caldwell, disclose a method of treating an open web material, preferably a fabric, with a curable liquid silicone polymer which is applied, under pressure, to the fabric. Caldwell further requires that the silicone polymer be cured by heat or radiation. Additionally, Caldwell calls for localized shear forces sufficient to work the hydrophobizing composition into the article to be treated. A disadvantage of this process is the requirement that excess silicone polymer is present on the treated article and must be wiped away during the finishing process.